1. Technical Field
The present invention relates to wireless communications and, more particularly, to methods of transmitting and processing data in a multi-cell cooperative wireless communication system.
2. Related Art
Next generation multimedia wireless communication system on which extensive research has been carried out is required to process various information, such as images, wireless data, etc., at a higher data transmission rate, beyond the voice-oriented services provided at an early stage.
Thus, Orthogonal Frequency Division Multiplexing (OFDM) having a high data transmission rate has recently attracted much attention. The OFDM is a multi-carrier modulation scheme that divides a frequency band into a plurality of orthogonal subcarriers to transmit data. Orthogonal Frequency Division Multiple Access (OFDMA) allows multiple users to transmit data simultaneously by combining the OFDM with Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), or Code Division Multiple Access (CDMA).
The wireless communication system includes a base station (BS) and at least one user equipment (UE). The user equipment may be fixed or movable and referred to as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, etc. The base station generally indicates a fixed station which communicates with the user equipment and referred to as a Node-B, a base transceiver system (BTS), an access point (AP), etc. Hereinafter, uplink (UL) means communication from the user equipment to the base station, and downlink (DL) means communication from the base station to the user equipment.
The wireless communication system has a cell structure to provide an efficient system configuration. The cell is one of a plurality of areas divided from a large area to efficiently use frequencies. In general, the base station is located at the center of the cell to serve the user equipment, and the cell is defined as a service area to which one base station provides a communication service.
When neighboring cells of the OFDM/OFDMA system in a multi-cell environment use the same subcarrier, it may cause interference to users, which is referred to as inter-cell interference. Especially, the inter-cell interference may have a significant effect on the user equipment located near the boundary of the cell. In the downlink, the user equipment located near the boundary of the cell receives strong interference from the neighboring cell. In the uplink, the user equipment located near the boundary of the cell causes strong interference to the neighboring cell and, further, has a low transmission rate due to path loss in the serving cell.
In order to reduce the inter-cell interference, the neighboring cells may use different subcarriers; however, radio resources that one base station can use is significantly reduced.
A multi-cell cooperative scheme has been proposed to reduce the inter-cell interference in the multi-cell environment. With the use of the multi-cell cooperative scheme, it is possible to improve communication performance of the user equipment located near the boundary of the cell. In connection with this, an extensive discussion on various methods of transmitting and processing data using the multi-cell cooperative scheme has continued to progress.